First-principles study of short range order and instabilities in AuCu, AuAg and AuPd alloys

First-Principles Study on the Elastic Mechanical Properties and Anisotropies of Gold–Copper Intermetallic Compounds

In this study, first-principles calculations were utilized to investigate the lattice constants, elastic constants, and mechanical properties of gold–copper (Au–Cu) intermetallic compounds (IMCs), including AuCu3, AuCu, and Au3Cu. We also verified the direction dependence of the Young’s modulus, shear modulus, and Poisson’s ratio of the compounds. The calculated lattice parameters agreed with the experimental data, and the single-crystal elastic constants, elastic modulus E, shear modulus G, bulk modulus B, and Poisson’s ratio ν were calculated. For the Young’s and shear moduli, AuCu3 showed the highest anisotropy, followed by AuCu and Au3Cu. The Poisson’s ratios of AuCu3 and Au3Cu crystals were isotropic on (100) and (111) crystal planes and anisotropic on the (110) crystal plane. However, the Poisson’s ratio of the AuCu crystal was anisotropic on (100) and (111) crystal planes and isotropic on the (110) crystal plane.

First-principles KKR-CPA calculation of interactions between concentration fluctuations

The aim of this work is to develop the method of calculating atomic interactions in metals and semiconductors on the basis of first-principles electronic structure calculation. A new method to calculate the atomic interactions in the framework of KKR-CPA is proposed. In this approach two specific atoms embedded in a CPA medium are considered and the effects of both electron-electron interactions and multiple scattering, which are neglected in the generalized perturbation method (GPM), are fully taken into account. The calculated atomic interactions show that these effects are important for alloys containing transition-metal alloys such as FeAl. On the other hand, in the case of AuCu, where the d states lie considerably below the Fermi level, the effects are less important.